Description
Return a parallel-axis inertia contribution.
Mechanical inertia, torque and muscle-force projections require compatible axes, origins and geometric assumptions. A parallel-axis contribution, planar moment or ideal pennation factor is one local model term rather than a full anatomical load or muscle-activation calculation.
Return a parallel-axis inertia contribution.
When to use this tool
Use Segment Mass Moment Contribution when evaluating the stated segment, moment, inertia or ideal muscle-geometry term.
How to use the tool and how it works
- Enter mass, centroidDistance, centroidalInertia. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read parallelAxisTerm, totalInertia. Use the output convention below.
Return a parallel-axis inertia contribution. Require mass and centroidalInertia >= 0; parallelAxisTerm = mass*centroidDistance², totalInertia adds centroidalInertia.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| mass | Mass | Required. Finite number; minimum 0. |
| centroidDistance | Centroid Distance | Required. Finite number. |
| centroidalInertia | Centroidal Inertia | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| parallelAxisTerm | Parallel Axis Term | Required. Finite number. |
| totalInertia | Total Inertia | Required. Finite number. |
{
"input": {
"mass": 2,
"centroidDistance": 3,
"centroidalInertia": 1
},
"output": {
"parallelAxisTerm": 18,
"totalInertia": 19
}
}Limitations and assumptions
- Inertias must refer to parallel axes and compatible mass/length units; no segment anatomy or full inertia tensor is inferred.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use verified anatomy and calibration, a consistent coordinate frame and a complete appropriate mechanical model for actual loading or clinical interpretation.
References
Similar or alternative tools
- Segment Inertia Unit Factor
Convert moment of inertia with supplied unit factors.
- Segment Inertia Parallelaxis Reference Offset
Return inertia about a shifted parallel axis.